WO2018147251A1 - Thermally adhesive sheath-core conjugate fiber and tricot fabric - Google Patents

Abstract

Provided is a thermally adhesive sheath-core conjugate fiber which has low fuzz generation in a high-order process, exhibits excellent high-order passability even in uses, such as tricot use and the like, requiring a high quality level, enables a woven or knitted fabric having excellent strength, dimensional stability, and durability after thermal adhesion, and has an excellent quality level as a flow path material of a liquid filtration membrane. The thermally adhesive sheath-core conjugate fiber has, as a core part, a polyester having a melting point of at least 250˚C, and has, as a sheath part, a polyester having a melting point which is at least 215˚C and is 20-35˚C lower than the melting point of the polyester constituting the core part. The thermally adhesive sheath-core conjugate fiber is characterized by having a strength of 3.8 cN/dtex or higher and an elongation of 35% or higher.

Description

Heat-adhesive core-sheath composite fiber and tricot knitted fabric

The present invention has less fuzz generation in high-order processes, is excellent in high-order passage even in applications with high quality requirements such as tricot use, and the woven or knitted fabric after heat bonding is excellent in strength, dimensional stability, and durability. The present invention relates to a heat-adhesive core-sheath composite fiber excellent in quality as a flow passage material for a liquid filtration membrane.

Polyester fibers are suitable as raw materials for clothing, industrial materials, etc. due to their excellent dimensional stability, weather resistance, mechanical properties, durability, and productivity that can be mass-produced relatively inexpensively. Used in applications.

In recent years, after using polyester fibers as woven or knitted fabrics, heat treatment such as calendering is applied to water treatment membranes, filter materials, interior materials such as chair upholstery and partitioning, and other clothing applications. Therefore, the use of heat-adhesive polyester fibers that can improve the shape retention and rigidity of the fabric by partially melting the fibers and thermally bonding the fibers to each other is progressing. Above all, the demand for water treatment membranes is increasing year by year in order to eliminate the serious water shortage caused by population growth mainly in the Middle East and Africa. However, the demand for a polyester tricot channel material in which a polyester tricot knitted fabric is thermally bonded is increasing rapidly.

As the polyester fiber having thermal adhesiveness, a yarn composed of two or more kinds of polyesters having different melting points or softening points is suitable. As the mode, for example, mixed yarn made of filament yarn, core-sheath type or side-by-side type composite fiber can be mentioned. Compared to a mixed yarn in which filaments having different melting points are mixed at the single yarn level, a composite fiber composed of polymers having different melting points is superior in quality after thermal bonding. In particular, a core-sheath composite yarn excellent in quality such as productivity of raw yarn and surface smoothness of the fabric after heat treatment, and the sheath component is composed of a component having a melting point or a softening point lower than that of the core component. Sheath-type composite fibers are actively used.

As the heat-adhesive core-sheath type composite fiber, a core-sheath type composite fiber having a polyester whose main repeating unit is ethylene terephthalate as a core part and a polymer having a softening temperature of 130 to 200 ° C. as a sheath part (Patent Document 1) Has been proposed.

According to the core-sheath-type conjugate fiber, it has a predetermined strength and elongation characteristic, does not cause misalignment due to displacement at the thermal bonding intersection, and does not generate wrinkles. Is done. However, as a preferred composition of the polymer used for the sheath component, the polymer in the sheath portion has a low crystallinity having no clear melting point, as exemplified by polyester copolymerized with isophthalic acid. For this reason, when the woven or knitted fabric made of the core-sheath type composite fiber is heat-bonded, unevenness occurs in the bonding between the composite fibers, resulting in dimensional stability, variation in the strength and elongation of the fabric, and the like. There was a problem of poor quality when used as a material.

On the other hand, a core-sheath type composite fiber in which 90 mol% or more of repeating units have a core made of a polymer composed of ethylene terephthalate and 60 to 90 mol% of repeating units have a copolymer polybutylene terephthalate made of butylene terephthalate as a sheath. (Patent Document 2) has been proposed.

According to the core-sheath type composite fiber, the sheath component is imparted with appropriate crystallinity, and since the fiber physical properties such as the boiling water shrinkage rate and the peak temperature of the heat shrinkage stress are good, the heat of good quality. It is said that a bonded knitted or knitted product can be obtained.

In addition, a tricot knitted fabric using the heat-bondable core-sheath composite fiber described in Patent Document 3 and Patent Document 4 has also been reported. In these technologies, a polyester whose core component has a significantly low melting point is used compared to the high melting point polyester of the core component, and if the spinning temperature is set only from the melting point of the core component polyester, the thermal degradation of the sheath component proceeds. easy. On the other hand, if the spinning temperature is lowered in consideration of the melting point of the sheath component polyester, the high elongation property of the core component cannot be exhibited to the maximum, so that the composite fiber is inferior in the strong elongation.

JP 62-184119 A JP 2000-119918 A JP 2011-245454 A JP 2014-070279 A

Since the core-sheath type composite fiber described in Patent Document 2 has poor strength and elongation, it is difficult to develop into a tricot application in which high-tension and high-speed processing is performed, and the quality defect of the raw yarn such as fluff is prominent as a defect of the fabric. There was a problem. Moreover, since the melting point of the sheath component is low, the heat bonding temperature after weaving and knitting cannot be increased, so that the shrinkage of the composite fibers constituting the fabric is insufficient, and high dimensional accuracy is required in designing the fabric. In applications such as a water treatment membrane channel material, there was a problem in dimensional stability when used for a long time under high pressure. In addition, the heat-adhesive core-sheath type composite fibers described in Patent Document 3 and Patent Document 4 have poor strength, so that not only the high-order passability is low but also the strength when used as a fabric is insufficient. Thus, there is a problem that the durability when used as a flow path material for a long time is inferior. Further, for the same reason as in Patent Document 2, since the thermal bonding temperature after weaving and knitting cannot be increased, shrinkage of fibers constituting the fabric is insufficient, and water treatment is required which requires high dimensional accuracy in the design of the fabric. In applications such as membrane channel materials, there was still a problem with dimensional stability when used for a long time under high pressure.

The present invention eliminates the problems of the prior art, has less fuzz generation in high-order processes, is excellent in high-order passage even in applications with high quality requirements such as tricot use, and the woven or knitted fabric after heat bonding has strength, dimensions Provided is a heat-adhesive core-sheath composite fiber that is excellent in stability and durability and excellent in quality as a flow passage material for a liquid filtration membrane.

In order to solve the above problems, the present invention has the following configuration.
(1) A core-sheath type composite fiber having a polyester having a melting point of 250 ° C. or higher as a core, a melting point of 215 ° C. or higher and a polyester having a melting point 20 to 35 ° C. lower than that of the polyester constituting the core. Is a heat-adhesive core-sheath-type composite fiber, characterized by having a tensile strength of 3.8 cN / dtex or more and an elongation of 35% or more.
(2) The heat-adhesive core-sheath conjugate fiber according to (1), wherein the core-sheath conjugate fiber has a total fineness of 30 dtex or more and a single yarn fineness of 3.0 dtex or less.
(3) A tricot knitted fabric comprising the heat-adhesive core-sheath composite fiber according to (1) or (2) in its configuration.

According to the present invention, there is little fluffing in a high-order process, excellent high-order passability even in applications with high quality requirements such as tricot use, and the woven or knitted fabric after heat bonding has strength, dimensional stability, and durability. It is possible to provide a heat-bondable core-sheath composite fiber that is excellent and excellent in quality as a flow passage material for a liquid filtration membrane.

FIG. 1 shows an example of a single yarn cross-sectional shape of a heat-adhesive core-sheath composite fiber preferably used in the present invention. FIG. 2 is an example of a single yarn cross-sectional shape of the thermoadhesive core-sheath conjugate fiber of the present invention, and is a view for explaining the cross-sectional eccentricity.

Hereinafter, the heat-adhesive core-sheath composite fiber of the present invention will be described in detail.
The core-sheath type composite fiber of the present invention is composed of a polyester having a melting point of the core component of 250 ° C. or higher, a polyester having a melting point of 215 ° C. or higher, and 20 to 35 ° C. lower than the melting point of the polyester constituting the core. The

By setting the melting point of the core component polyester to 250 ° C. or higher, the spinning temperature can be increased to such an extent that the strength and elongation characteristics of the polyester can be maximized, and the strength and durability when used as a fabric are excellent. The melting point of the core component polyester is preferably 270 ° C. or less from the practical upper limit. It is preferable that the melting point of the core component polyester is 270 ° C. or lower because it is not necessary to perform spinning at an extremely high temperature and spinning can be performed using a general-purpose melt spinning apparatus. More preferably, it is 253 degreeC or more and 260 degrees C or less.

The melting point of the sheath component polyester is 215 ° C or higher, preferably 250 ° C or lower. It is preferable that the melting point of the sheath component polyester is 250 ° C. or lower because a general-purpose apparatus can be used when the fabric is thermally bonded, and fuming caused by the oil component in the thermal bonding treatment can be suppressed. More preferably, it is 220 degreeC or more and 235 degreeC or less. By making the melting point difference between the sheath component polyester and the core component polyester 20 ° C. or more, the thermal bonding temperature of the fabric can be made sufficiently lower than the melting point of the core component polyester, It can be a durable fabric. Further, by setting the difference in melting point to 35 ° C. or less, the spinning temperature can be set to a temperature that maximizes the strength of the core component polyester and suppresses the thermal degradation of the sheath component polyester as much as possible. This is a composite fiber that is superior in quality and excellent in quality with little raw yarn fluff. The difference in melting point between the sheath component polyester and the core component polyester is preferably 23 ° C. or higher and 30 ° C. or lower.

Also, the softening temperature of the core component polyester is preferably 245 ° C. or higher, and the softening temperature of the sheath component polyester is preferably 205 ° C. or higher. It is preferable that the softening temperature of the core component polyester is 245 ° C. or higher because when the fabric is heat-bonded at the melting point or higher of the sheath component polyester, the dimensional change is small and the fabric form is stable. The softening temperature of the core component polyester is more preferably 250 ° C. or higher. The upper limit temperature of the softening temperature of the core component polyester is practically 270 ° C.

It is preferable that the softening temperature of the sheath component polyester is 205 ° C. or higher because there is no fusion to the heater during heat setting in the processing step, and the high-speed passage is stable. The softening temperature of the sheath component polyester is more preferably 215 ° C. or higher. By setting the melting point of the sheath component polyester to 215 ° C. or higher and the softening point to 205 ° C. or higher, the thermal bonding temperature after forming the fabric can be sufficiently increased. Is preferable because the dimensional stability of the final product is improved. The upper limit temperature of the softening temperature of the sheath component polyester is practically 250 ° C.

As the core component polyester, any polyester can be selected as long as the melting point is within the above range, but polyethylene terephthalate (hereinafter referred to as PET) is preferable from the viewpoint of dimensional stability and strong elongation characteristics. PET is a polyester obtained using terephthalic acid as the main acid component and ethylene glycol as the main glycol component. The core component polyester may appropriately include a copolymer component as long as the melting point is within the above-described range. Examples of the copolymerizable compound include PET, dicarboxylic acids such as isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimer acid, sebacic acid, 5-sodium sulfoisophthalic acid, ethylene glycol, diethylene glycol, 2 , 2-dimethyl-1,3-propanediol, butanediol, neopentyl glycol, cyclohexanedimethanol, polyethylene glycol, polypropylene glycol, bisphenol A ethylene oxide adduct, and the like. From the viewpoint of the strength and elongation characteristics, it is more preferable that the PET is a homo-PET comprising 100% repeating units of ethylene terephthalate. If necessary, inorganic fine particles such as titanium dioxide as a matting agent and silica fine particles as a lubricant may be added.

As the sheath component polyester, any polyester can be selected as long as the melting point is within the above-mentioned range, but in addition to PET, polytrimethylene terephthalate and polybutylene terephthalate are preferable. When PET is used as the core component polyester, it is particularly preferable to use PET as the sheath component polyester in consideration of suppression of peeling at the composite interface. As the sheath component polyester, an arbitrary copolymer component can be added at an arbitrary ratio as long as the melting point is within the above-mentioned range. However, when the copolymer PET is composed of 70% by mole or more of ethylene terephthalate repeating units, Moderate crystallinity can be imparted, and spinning operability is stabilized. In addition, when the fabric is thermally bonded, thermal bonding unevenness is less likely to occur, which is preferable. More preferably, 80 mol% or more is a copolymerized PET composed of ethylene terephthalate repeating units. Even when a polymer other than PET is used as the sheath component polyester, a copolymer component can be appropriately added within a range that does not impair the raw yarn productivity and the quality of the fabric after the thermal bonding treatment. As a copolymerization component, arbitrary components, such as the above-mentioned copolymerization component, can be copolymerized. In addition, inorganic fine particles such as titanium dioxide as a matting agent and silica fine particles as a lubricant may be added as needed, regardless of the polymer species selected.

Next, the intrinsic viscosity (hereinafter referred to as IV) of the composite fiber is preferably 0.55 to 0.75. When the IV is 0.55 or more, the degree of polymerization is not too low, and it is preferable because the toughness sufficient for the composite fiber to withstand practical use can be achieved. On the other hand, if the IV is 0.75 or less, the IV is not too high at the time of spinning, there is no need to perform extreme high temperature spinning, the increase in the amount of COOH during melt spinning can be suppressed, and melt fracture may occur. This is preferable because a uniform composite fiber is obtained and the toughness is not lowered. More preferably, IV is in the range of 0.60 to 0.70.

FIG. 1 is a schematic cross-sectional view of a core-sheath type composite fiber of the present invention, which shows a core-sheath type composite fiber 10 in which a core component 1 is surrounded by a sheath component 2.

The cross-sectional shape of the composite fiber is not particularly limited as long as the high melting point component is disposed in the core portion and the low melting point component is disposed in the sheath shape covering the core portion, but the sheath component completely covers the core component, and the core component It is preferable that there is no exposure. In addition, for the stability of physical properties such as the productivity of raw yarn and Uster spots U%, the eccentricity of the center of gravity of the core component with respect to the center of gravity of the entire composite fiber is preferably 5% or less in the cross section of the composite fiber. An eccentricity of 5% or less is preferable because a coil-like crimp does not appear even if the combination of the core component and the sheath component is a combination that causes a shrinkage difference, and the fabric quality is excellent. More preferably, the eccentricity is 1% or less.

The cross-sectional outer peripheral shape of the composite fiber is preferably a substantially circular shape having a flatness expressed by A / B of 1.1 or less, where A is the major axis and B is the minor axis. By adopting such a shape, it is possible to uniformly receive the force when subjected to external tension, and it is preferable because variations in the strength and elongation of the composite fiber in the SS curve are reduced. More preferably, the aspect ratio is 1.0.

The composite ratio of the core component to the sheath component in the core-sheath composite fiber is preferably such that the cross-sectional area ratio is core: sheath = 40: 60 to 90:10, and more preferably 55:45 to 75:25. By making the composite ratio within the above range, it is preferable because the composite fiber can be stably spun and excellent in high elongation, less fuzz is generated, and the high elongation can be maintained even when the fabric is thermally bonded.

The content of the inorganic particles contained in the core component is preferably 3.0% by weight or less because the toughness is improved, and more preferably 0.5% by weight or less. The content of the inorganic fine particles contained in the sheath component is preferably 0.05% by weight or more because process passability is improved. More preferably, the content of the inorganic fine particles contained in the sheath component is 0.05% by weight or more and 0.5% by weight or less without excessive wear of the guide during the process, when used as a flow path material, It is preferable because unnecessary inorganic particles are not dropped off. The inorganic fine particles are preferably titanium oxide from the viewpoint of process passability as a composite fiber.

In the composite fiber of the present invention, the total fineness is preferably 30 dtex or more. By setting the total fineness to 30 dtex or more, sufficient strength and rigidity can be ensured even by heat bonding treatment, and when used as a flow path material, a sufficient amount of permeate flows even if water pressure acts. Can be secured. The total fineness is preferably 90 dtex or less, more preferably 40 dtex or more. By setting the total fineness to 90 dtex or less, the fabric can be thinned, and when used as a flow path material, the number of layers per unit formed by bonding the filtration membrane and the flow path material can be increased.

The single yarn fineness of the composite fiber is preferably 3.0 dtex or less. By setting the single yarn fineness to 3.0 dtex or less, the specific surface area is large, it can be uniformly heat-bonded even in a short-time heat bonding treatment, and the fabric strength can be prevented from being lowered by the heat bonding treatment. A fabric can be obtained. The single yarn fineness is preferably 0.7 dtex or more, and more preferably 1.5 dtex or more and 2.5 dtex or less. By setting the single yarn fineness to 0.7 dtex or more, there is little yarn unevenness and raw yarn fluff, and stable yarn production is possible. It is preferable because an appropriate rigidity can be obtained.

The strength of the composite fiber is 3.8 cN / dtex or more, and the elongation is 35% or more. By setting the strength to 3.8 cN / dtex or more, the strength is high when used as a fabric, and the durability when used as a flow path material is excellent. The practical upper limit is a strength of 7.0 cN / dtex. Moreover, by setting the elongation to 35% or more, it is possible to prevent the fluff of the original yarn, and further, the warp fluff at the time of weaving and knitting, the yarn breakage at the time of knitting is excellent, and the high-passability is excellent, and there are few defects. It becomes an excellent fabric. More preferably, the elongation is 35 to 50%. A woven or knitted fabric obtained by setting the elongation to 50% or less is preferable because of excellent dimensional stability.

In order to obtain a highly uniform fabric, it is preferable that the Worcester unevenness U%, which is an index of thickness unevenness in the fiber longitudinal direction of the composite fiber, is 1.4% or less. Wooster spots U% of 1.4% or less is preferable because the surface of the fabric after thermal bonding becomes smooth and a uniform channel can be formed when used as a channel material. More preferably, the Wooster plaque U% is 1.0% or less.

The dry heat shrinkage of the composite fiber is preferably 20% or less. It is preferable to set the dry heat shrinkage rate to 20% or less because dimensional changes due to thermal bonding treatment can be suppressed. The practical lower limit is a dry heat shrinkage of 2.0%.

A preferred yarn production method for achieving the object of the present invention will be described.
As the die used for the melt spinning method of the heat-adhesive core-sheath composite fiber of the present invention, an existing composite spinning die can be used.

Examples of the melting method include a method using a pressure melter and a method using an extruder, but melting using an extruder is preferable from the viewpoint of efficiency and suppression of decomposition. The melting temperature is preferably set to 10 to 40 ° C. higher than the melting point of the polymer used.

A preferable spinning temperature is 280 to 295 ° C. More preferably, the spinning temperature is 285 ° C to 293 ° C. By adopting such a spinning temperature, it is possible to obtain a composite fiber having high toughness and good spinning properties. In order to mitigate the rapid cooling immediately below the base, a heater may be provided under the base.

It is preferable to shorten the melt passage time and the heating time from melting to discharge as much as possible because the molecular weight reduction of the core component and the sheath component can be suppressed. Both the core component and sheath component are melted and kneaded separately, precisely discharged and weighed through a heating zone, passed through a filtration layer supplemented with foreign matter, and discharged and formed into a core and sheath using a composite die.・ Cooled. When the polymer residence time, which is the transit time from melting to ejection, is within 30 minutes, thermal degradation of the polymer can be reduced, IV reduction can be suppressed, and yarn toughness reduction can be prevented. Moreover, since the increase in the amount of COOH in the composite fiber can be suppressed, fluff is suppressed, heat resistance is excellent, high-order passage property is excellent, and durability when used as a fabric can be improved, which is preferable. More preferably, the polymer residence time is 20 minutes or less.

From the balance between strong elongation and productivity, the die surface temperature is preferably 270 ° C. or higher and 290 ° C. or lower. By setting the base surface temperature to 270 ° C. or higher, the core component characteristics can be maximized, and a yarn excellent in high elongation can be obtained. By setting the die surface temperature to 290 ° C. or less, an increase in yarn breakage due to deposition of polymer hydrolyzate directly under the die is suppressed, and this is preferable because it is excellent in raw yarn productivity.

The core-sheath type composite fiber of the present invention is not only a two-step method in which the discharged polymer is once wound up as an undrawn yarn and then drawn, as well as a direct spinning drawing method or a high-speed spinning method in which spinning and drawing steps are continuously performed. It can be produced by any one-step method.

The stretching temperature is preferably 60 ° C. or higher and 100 ° C. or lower, which is near the glass transition temperature of the undrawn yarn. Uniform stretching can be achieved by setting the stretching temperature to 60 ° C. or higher, and productivity deterioration due to fusion to a stretching roll or spontaneous elongation of fibers can be prevented by setting the stretching temperature to 100 ° C. or lower. More preferably, the stretching temperature is 75 ° C. or higher and 95 ° C. or lower.

In addition, after drawing, it is preferable to heat-set at a temperature at which the crystal speed of the undrawn yarn is maximized, and it is preferably set to 110 ° C. or higher and 180 ° C. or lower. Heat setting at 110 ° C. or higher is preferable because it can not only promote fiber crystallization and increase strength, but also stabilize various yarn properties such as shrinkage stress and dry heat shrinkage. Moreover, it is preferable to heat-set at 180 ° C. or lower because productivity deterioration due to fusion of the composite fiber to the heat-setting device can be prevented.

Hereinafter, specific examples will be described. In addition, the main measured value of the Example was measured with the following method.

(1) Intrinsic viscosity (IV)
Ηr of the definition formula is obtained by dissolving 0.8 g of a sample in 10 mL of O-chlorophenol (OCP) having a purity of 98% or more, and obtaining the relative viscosity ηr using an Ostwald viscometer at a temperature of 25 ° C. according to the following formula: Intrinsic viscosity (IV) was calculated.
ηr = η / η0 = (t × d) / (t0 × d0)
Intrinsic viscosity (IV) = 0.0242 ηr + 0.2634
[Η: viscosity of polymer solution, η0: OCP viscosity, t: solution drop time (second), d: solution density (g / cm ³ ), t0: OCP drop time (second), d0: OCP Density (g / cm ³ )].

(2) Melting point Using a differential scanning calorimetry (DSC) Q100 manufactured by TA Instruments, 10 mg of the dried sample was weighed, sealed in an aluminum pan, and heated from room temperature to 300 ° C. under a nitrogen atmosphere at a rate of temperature increase of 16 ° C./min. Measured with After the first measurement (1st run), the sample was held for 5 minutes and then rapidly cooled to room temperature. The second measurement (2nd run) was continuously performed, and the peak top temperature of the melting peak in 2nd run was taken as the melting point.

(3) Softening temperature Using a thermal mechanical device (TMA / SS-6000) manufactured by Seiko Instruments Inc., place the dried sample on the sample stage and measure using a needle probe with a tip diameter of 1.0 mm. Measurement was performed at a temperature increase rate of 16 ° C./min from room temperature to 300 ° C. under a load of 10 g and a nitrogen atmosphere. The temperature at the start of displacement was defined as the softening temperature.

(4) Cross-section eccentricity The cross-section of the fiber was observed using a Keyence Corporation microscope VHX-2000, each value was measured with the attached image analysis software, and the center-of-gravity position of the core component was determined as C1 (see FIG. 2). 3) When the center of gravity of the composite fiber is Cf (4 in FIG. 2) and the radius of the composite fiber is rf (5 in FIG. 2), the cross-sectional eccentricity is calculated from the following equation.
Cross-section eccentricity (%) = {| Cf−C1 | / rf} × 100.

(5) Cross-sectional flatness In the same manner as in (4), the cross-section of the composite fiber is observed, and the longest is the longest diameter A and the shortest is the shortest diameter B among the diameters passing through the center of the cross section. The rate was calculated.
Cross-sectional flatness = major axis A / minor axis B

(6) Fineness, strength, elongation, toughness Measured according to JIS L1013 (2010, chemical fiber filament yarn test method). The toughness was calculated by the following formula.
(Toughness) = (Strength) × (Elongation) ^0.5

(7) Wooster spots U%
Measurement was performed in the normal mode while feeding the yarn at a speed of 200 m / min for 5 minutes using a Zellerweger USTER TESTER 4-CX.

(8) Boiling water shrinkage rate, dry heat shrinkage rate Using a measuring machine with a frame circumference of 1.0 m, 10 casses were prepared and calculated according to the following formula. Incidentally, both the original length and the length after treatment were measured by applying a load {(display fineness (dtex) × 2) g}. Regarding the shrinkage treatment, the boiling water shrinkage was immersed in boiling water for 15 minutes, and the dry heat shrinkage was treated at 200 ° C. for 5 minutes.
Shrinkage rate (%) = {(original length (L1) −post-treatment length (L2)) / original length (L1)} × 100.

(9) The number of fluff defects Using a fly counter (MFC-120S) manufactured by Toray Engineering Co., Ltd., 48 composite fibers were measured and detected under the measurement conditions of unwinding speed = 500 m / min and measurement length = 50000 m. The number of fluff was counted. Based on the counted number of fluff, the following points were obtained.
3 points: all 48 are 0 2 points: the average number of 48 is less than 0.1, and the maximum number of 48 is 1 1 point: the average number of 48 is 0.1 or more. Less than 3 and the maximum number of 48 is 1 0 point: The average number of 48 is 0.3 or more, or the maximum number of 48 is 2 or more.

(10) High-passability After warping the conjugate fiber of the present invention, using the yarn obtained by the present invention for both the front yarn and the back yarn, using a tricot knitting machine (36 gauge) consisting of two sheets Thus, the following evaluation points were used according to the number of warp fluff detected and the number of knitting yarn breaks when knitting with a closed double denby structure.
3 points: warp fluff 0.3 pieces / less than 10 million m and knitting yarn breakage 0.5 times / less than 200 m 2 points: warp fluff 0.3 pieces / ten million m or more 0.6 pieces / 10 million m Less than knitting yarn break 0.5 times / 200 m, or warping fluff 0.3 pieces / less than 10 million m and knitting yarn breakage 0.5 times / 200 m or more and less than 1.0 times / 200 m 1 point: warping Fluff 0.3 / 10 million m or more and less than 0.6 / 10 million m and knitting yarn breakage 0.5 times / 200 m or more and less than 1.0 time / less than 200 m 0 point: Warp fluff 0.6 pieces / 10 million m or more, or knitting yarn breakage 1.0 times / 200 m or more.

(11) Strength of fabric after thermal bonding A tricot knitted fabric is prepared by the method of (10), heat-treated at a melting point of the sheath component + 10 ° C. in a pin tenter dryer under no load, and thermally bonded. Was made. The density of the fabric after heat bonding was adjusted so that the wale direction was 66 / 2.54 cm (= inch) and the course direction was 53 / 2.54 cm (= inch). The fabric strength after heat bonding was measured according to JIS 1096: 2010 (fabric and knitted fabric test method) in each of the wale (vertical) and course (horizontal) directions, and the following scores were obtained based on the strength values.
3 points: vertical 600 N / 5 cm or more and horizontal 100 N / 5 cm or more 2 points: vertical 500 N / 5 cm or more and less than 600 N / 5 cm and horizontal 100 N / 5 cm or more, or vertical 600 N / 5 cm or more and horizontal 80 N / 5 cm or more 100 N / 5 cm 1 Point: Vertical 500 N / 5 cm or more and less than 600 N / 5 cm and horizontal 80 N / 5 cm or more and less than 100 N / 5 cm 0 point: Vertical 500 N / 5 cm or horizontal 80 N / 5 cm.

(12) Channel material water resistance test (salt removal rate (%), water production (m ³ / day))
A tricot knitted fabric after heat bonding produced in the same manner as in (11) is sandwiched between two 150 μm thick RO separation membranes to form a spiral unit, and incorporated into a module having a diameter of 0.2 m and a length of 1 m. Then, seawater having a TDS (soluble evaporation residue) of 3.5% by weight was filtered at a liquid temperature of 25 ° C. with a differential pressure of 4.5 MPa for 5 days. After 5 days, the electric conductivity of the permeate was measured, and the removal rate of the magnesium sulfate salt was calculated. Further, the amount of permeated liquid after 5 days was measured, and the amount of fresh water produced per day was calculated. Based on the results of the test, the following evaluation points were used.
3 points: Magnesium sulfate salt removal rate of 99.8% or more and water production amount of 45 m ³ / day or more 2 points: Magnesium sulfate salt removal rate of 99.8% or more and water production amount of 40 m ³ / day or more of 45 m ³ / Day or the removal rate of magnesium sulfate salt is 99.0% or more and less than 99.8% and the amount of water produced is 45 m ³ / day or more 1 point: The removal rate of magnesium sulfate salt is 99.0% or more and 99.8% %, And the amount of water produced is 40 m ³ / day or more and less than 45 m ³ / day 0 point: The removal rate of magnesium sulfate salt is less than 99.0%, or the amount of water produced is less than 40 m ³ / day.

(13) Pass / Fail Judgment In the evaluation items (9) to (12), a case where all were 2 or more points was accepted, and a case where even one was 1 point or less was rejected.

Example 1
A homo-PET polymer of IV0.67 containing no titanium oxide (high melting point component, melting point 255 ° C.) and isophthalic acid and bisphenol A ethylene oxide adduct as the copolymer component are each 7.1 mol% based on the total acid component, A copolymerized PET polymer (low melting point component, melting point 230 ° C.) having a titanium oxide content of 0.05 wt% and IV 0.65 copolymerized with 4.4 mol% was prepared, and the high melting point component was 285 ° C. with an extruder. The low melting point component was melted at 260 ° C with an extruder, the spinning temperature was set at 290 ° C, weighed with a metering pump, filtered in a pack, and then with a nozzle nozzle as shown in FIG. It was discharged into a core-sheath composite type having a composite area ratio of 65:35 so that the cross-sectional shape of the concentric circular core-sheath was as follows (the cross-sectional eccentricity was 0% and the cross-sectional flatness was 1.0). At this time, it arrange | positioned so that a high melting component may become a core and a low melting component may become a sheath.

As the take-up device, a direct spinning method (DSD) is used which is consistently performed from drawing to winding, and the discharged polymer is set at a speed of 1728 m / min and a surface temperature of 85 ° C. through the cooling part and the oiling part. Then, the film was taken up by a take-up roll (first HR) and continuously drawn up to a heat treatment roll (second HR) set to 128 ° C. at 4489 m / min without being wound up, and stretched 2.6 times. The tension of the stretched and heat-treated yarns is adjusted with godet rollers (3rd GR and 4GR) set to speeds of 4549 m / min and 4584 m / min, respectively, and the tension is 0.20 cN / dtex at a speed of 4500 m / min. The cheese-like package was wound up to obtain a core-sheath type composite fiber of 56 dtex-24 filaments. The evaluation results for the obtained fibers are shown in Table 1. The Wooster spot U% was 0.4%, the boiling water shrinkage was 10.3%, and the dry heat shrinkage was 17.2%.

As shown in Table 1, it was excellent in high elongation and toughness, and it was good with little generation of raw yarn fluff. The resulting yarn was used for both the front yarn and the back yarn, and was knitted with a double denby structure using a tricot knitting machine (36 gauge) consisting of two pieces of warp. There were few, and it was excellent in high-order passage property. Furthermore, the fabric strength after heat bonding with a pin tenter at 240 ° C. (melting point of sheath component + 10 ° C.) is high, and when used as a channel material for a water treatment membrane, Excellent dimensional stability, and there was no damage or clogging of the channel material during continuous use, and a stable amount of fresh water could be secured while maintaining membrane performance.

Examples 2 to 4 and Comparative Examples 1 to 3
In Examples 2 to 4 and Comparative Examples 1 to 3, the melting points of the core component polyester and the sheath component polyester were changed using the copolymer components used in the sheath component of Example 1, respectively. In accordance with Example 1, except that an appropriate spinning temperature was adopted. The evaluation results are shown in Table 1.

Example 5
Example 5 was the same as Example 1 except that the spinning machine was changed from DSD to the two-step method and the spinning conditions were adjusted accordingly. The evaluation results are shown in Table 1.

Examples 6-7
Examples 6 to 7 were the same as Example 1 except that the shape of the discharge hole of the base was changed and the cross-sectional shape and the eccentricity of the core sheath were changed as shown in Table 2. The evaluation results are shown in Table 2.

Examples 8-11
Examples 8 to 11 were the same as Example 1 except that the fineness of the composite fiber and the number of filaments were changed as shown in Table 2. The evaluation results are shown in Table 2.

Examples 12-14
Examples 12 to 14 were the same as Example 1 except that the amount of titanium oxide added to the core component polyester and the sheath component polyester was changed as shown in Table 3. The evaluation results are as shown in Table 3.

Examples 15-17
Examples 15 to 17 were the same as Example 1 except that the discharge amounts of the core component polyester and the sheath component polyester were changed to the core: sheath ratio as shown in Table 3. The evaluation results are as shown in Table 3.

DESCRIPTION OF SYMBOLS 1 Core component 2 Sheath component 3 Center-of-gravity position of core component 4 Center-of-gravity position of composite fiber 5 Radius of composite fiber 10 Thermal adhesive core-sheath composite fiber

Claims (3)

2. A core-sheath type composite fiber having a polyester having a melting point of 250 ° C. or higher as a core, a polyester having a melting point of 215 ° C. or higher and a melting point 20 to 35 ° C. lower than that of the polyester constituting the core, and having a strength of 3. A heat-adhesive core-sheath type composite fiber characterized by having an elongation of 8 cN / dtex or more and an elongation of 35% or more. The heat-adhesive core-sheath composite fiber according to claim 1, wherein the core-sheath composite fiber has a total fineness of 30 dtex or more and a single yarn fineness of 3.0 dtex or less. A tricot knitted fabric comprising the heat-adhesive core-sheath composite fiber according to claim 1 or 2 in its configuration.

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